EP1231515B1 - Appareil lithographique et méthode de fabrication d'un dispositif - Google Patents

Appareil lithographique et méthode de fabrication d'un dispositif Download PDF

Info

Publication number
EP1231515B1
EP1231515B1 EP02250785A EP02250785A EP1231515B1 EP 1231515 B1 EP1231515 B1 EP 1231515B1 EP 02250785 A EP02250785 A EP 02250785A EP 02250785 A EP02250785 A EP 02250785A EP 1231515 B1 EP1231515 B1 EP 1231515B1
Authority
EP
European Patent Office
Prior art keywords
substrate
exposure
focal plane
projection
exposure area
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP02250785A
Other languages
German (de)
English (en)
Other versions
EP1231515A1 (fr
Inventor
Marcus Emile Joannes Boonman
Johannes Catharinus Hubertus Mulkens
Hans Butler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ASML Netherlands BV
Original Assignee
ASML Netherlands BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP01301116A external-priority patent/EP1231513A1/fr
Application filed by ASML Netherlands BV filed Critical ASML Netherlands BV
Priority to EP02250785A priority Critical patent/EP1231515B1/fr
Publication of EP1231515A1 publication Critical patent/EP1231515A1/fr
Application granted granted Critical
Publication of EP1231515B1 publication Critical patent/EP1231515B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/703—Non-planar pattern areas or non-planar masks, e.g. curved masks or substrates
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70258—Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system

Definitions

  • the present invention relates to a lithographic projection apparatus comprising:
  • patterning means as here employed should be broadly interpreted as referring to means that can be used to endow an incoming radiation beam with a patterned cross-section, corresponding to a pattern that is to be created in a target portion of the substrate; the term “light valve” can also be used in this context.
  • the said pattern will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit or other device (see below). Examples of such patterning means include:
  • Lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs).
  • the patterning means may generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. comprising one or more dies) on a substrate (silicon wafer) that has been coated with a layer of radiation-sensitive material (resist).
  • a target portion e.g. comprising one or more dies
  • a substrate silicon wafer
  • a layer of radiation-sensitive material resist
  • a single wafer will contain a whole network of adjacent target portions that are successively irradiated via the projection system, one at a time.
  • employing patterning by a mask on a mask table a distinction can be made between two different types of machine.
  • each target portion is irradiated by exposing the entire mask pattern onto the target portion in one go; such an apparatus is commonly referred to as a wafer stepper.
  • each target portion is irradiated by progressively scanning the mask pattern under the projection beam in a given reference direction (the "scanning" direction) while synchronously scanning the substrate table parallel or anti-parallel to this direction; since, in general, the projection system will have a magnification factor M (generally ⁇ 1), the speed V at which the substrate table is scanned will be a factor M times that at which the mask table is scanned.
  • M magnification factor
  • a pattern (e.g. in a mask) is imaged onto a substrate that is at least partially covered by a layer of radiation-sensitive material (resist).
  • the substrate Prior to this imaging step, the substrate may undergo various procedures, such as priming, resist coating and a soft bake. After exposure, the substrate may be subjected to other procedures, such as a post-exposure bake (PEB), development, a hard bake and measurement/inspection of the imaged features.
  • PEB post-exposure bake
  • This array of procedures is used as a basis to pattern an individual layer of a device, e.g. an IC.
  • Such a patterned layer may then undergo various processes such as etching, ion-implantation (doping), metallization, oxidation, chemo-mechanical polishing, etc., all intended to finish off an individual layer. If several layers are required, then the whole procedure, or a variant thereof, will have to be repeated for each new layer. Eventually, an array of devices will be present on the substrate (wafer). These devices are then separated from one another by a technique such as dicing or sawing, whence the individual devices can be mounted on a carrier, connected to pins, etc.
  • the projection system may hereinafter be referred to as the "lens"; however, this term should be broadly interpreted as encompassing various types of projection system, including refractive optics, reflective optics, and catadioptric systems, for example.
  • the radiation system may also include components operating according to any of these design types for directing, shaping or controlling the projection beam of radiation, and such components may also be referred to below, collectively or singularly, as a "lens”.
  • the lithographic apparatus may be of a type having two or more substrate tables (and/or two or more mask tables). In such "multiple stage” devices the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposures. Dual stage lithographic apparatus are described, for example, in US 5,969,441 and WO 98/40791 , incorporated herein by reference.
  • the position of the focal plane can vary according to the position of the mask, illumination and imaging settings in the illumination and projection systems and due to, for example, temperature and/or pressure variations in the apparatus, during a series of exposures.
  • a sensor such as a transmission image sensor (TIS) or a reflection image sensor (RIS) and then position the wafer surface in the focal plane.
  • TIS transmission image sensor
  • RIS reflection image sensor
  • the exact shape and position of the wafer surface can be measured and the wafer height and tilt positions for the exposure can then be optimised to minimise defocus predicted relative to that measured wafer surface. Since the focal plane of the projection system will generally be flat and the wafer surface will generally not be flat, there will always be some residual defocus which cannot be compensated for by levelling procedures.
  • US 5,202,748A discloses a lithographic projection apparatus in which the substrate being exposed is deformed to be more flat and aberrations in the optical train are reduced by adjusting a deformable turning mirror.
  • US 5,142,132 discloses a semiconductor wafer stepper including an interferometer camera to provide depth of focus and aberration information which is used to control a deformable mirror.
  • An object of the present invention is to provide a system and a method for controlling a lithographic projection apparatus to further improve focus across the entire exposure area.
  • the focal plane is generally arranged to be as flat as possible and the substrate height and/or tilt are controlled to minimise defocus, inevitably leave some residual defocus as the wafer surface is generally not exactly flat.
  • control of the wafer height and tilt is integrated with control of the shape of the focal plane. Then, low order (height & tilt) corrections can be effected by positioning the substrate and high order corrections can be effected by adjustments to the shape of the focal plane. Also, low order effects of high order adjustments to the shape of the focal plane can be compensated for in positioning of the substrate.
  • the present invention can therefore provide improved imaging by reducing defocus across the entire exposure area. This improves imaging quality on all exposure areas and also makes possible focussing on exposure areas having curved surfaces that would previously have exceeded defocus limits.
  • the present invention can make use of all available manipulators in the projection system to adjust elements that affect the shape of the focal plane.
  • manipulators are provided with suitable actuators, e.g. motors, piezoelectric actuators, solenoids, etc., to enable the control means to adjust the elements to which the manipulators are connected.
  • the adjustable elements may include elements specifically provided for the present invention or provided for other purposes such as correcting field curvature introduced by changes in magnification, or correcting astigmatisms in the lenses.
  • the adjustable elements may have their position and/or orientation in any of the six degrees of freedom changed by the manipulators. Additionally, it is possible to adjust the shape of the element.
  • UV radiation and “beam” are used to encompass all types of ultraviolet radiation (e . g . with a wavelength of 365, 248, 193, 157 or 126 nm).
  • Figure 1 schematically depicts a lithographic projection apparatus according to a particular embodiment of the invention.
  • the apparatus comprises:
  • the source LA (e . g . a Hg lamp or an excimer laser) produces a beam of radiation.
  • This beam is fed into an illumination system (illuminator) IL, either directly or after having traversed conditioning means, such as a beam expander EX, for example.
  • the illuminator IL may comprise adjusting means AM for setting the outer and/or inner radial extent (commonly referred to as ⁇ -outer and ⁇ -inner, respectively) of the intensity distribution in the beam.
  • it will generally comprise various other components, such as an integrator IN and a condenser CO.
  • the beam PB impinging on the mask MA has a desired uniformity and intensity distribution in its cross-section.
  • the source LA may be within the housing of the lithographic projection apparatus (as is often the case when the source LA is a mercury lamp, for example), but that it may also be remote from the lithographic projection apparatus, the radiation beam which it produces being led into the apparatus (e.g. with the aid of suitable directing mirrors); this latter scenario is often the case when the source LA is an excimer laser.
  • the current invention and Claims encompass both of these scenarios.
  • the beam PB subsequently intercepts the mask MA, which is held on a mask table MT. Having traversed the mask MA, the beam PB passes through the lens PL, which focuses the beam PB onto a target portion C of the substrate W. With the aid of the interferometric measuring means IF, the substrate tables WTa, WTb can be moved accurately by the second and third positioning means, e . g . so as to position different target portions C in the path of the beam PB. Similarly, the first positioning means can be used to accurately position the mask MA with respect to the path of the beam PB, e.g. after mechanical retrieval of the mask MA from a mask library, or during a scan.
  • the object tables MT, WTa, WTb will be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which are not explicitly depicted in Figure 1 .
  • the mask table MT may just be connected to a short stroke actuator, or may be fixed.
  • the second and third positioning means may be constructed so as to be able to position their respective substrate tables WTa, WTb over a range encompassing both the exposure station under projection system PL and the measurement station under the measurement system MS.
  • the second and third positioning means may be replaced by separate exposure station and measurement station positioning systems for positioning a substrate table in the respective exposure stations and a table exchange means for exchanging the substrate tables between the two positioning systems.
  • Suitable positioning systems are described, inter alia, in WO 98/28665 and WO 98/40791 mentioned above. It should be noted that a lithography apparatus may have multiple exposure stations and/or multiple measurement stations and that the numbers of measurement and exposure stations may be different than each other and the total number of stations need not equal the number of substrate tables. Indeed, the principle of separate exposure and measurement stations may be employed even with a single substrate table.
  • the depicted apparatus can be used in two different modes:
  • the height of the wafer surface ZWafer relative to a physical reference surface of the substrate table is mapped.
  • This process is carried out at the measurement station using a first sensor, referred to as the level sensor, which measures the vertical (Z) position of the physical reference surface and the vertical position of the wafer surface, ZLS, at a plurality of points, and a second sensor, for example a Z-interferometer, which simultaneously measures the vertical position of the substrate table, ZIF at the same points.
  • the substrate table carrying the wafer is then transferred to the exposure station and the vertical position of the physical reference surface is again determined.
  • the height map is then referred to in positioning the wafer at the correct vertical position during the exposure process. This procedure is described in more detail below with reference to Figures 3 to 6 .
  • the physical reference surface may be any convenient surface whose position in X, Y and Z on the substrate table will not change during processing of a wafer in the lithographic apparatus and, most importantly, in the transfer of the substrate table between measurement and exposure stations.
  • the physical reference surface may be part of a fiducial containing other alignment markers and the surface should have such properties as to allow its vertical position to be measured by the same sensor as measures the vertical position of the wafer surface.
  • the physical reference surface may be a reflective surface in a fiducial in which is inset a so-called transmission image sensor (TIS). The TIS is described further below.
  • the level sensor may be, for example, an optical sensor; alternatively, pneumatic or capacitive sensors (for example) are conceivable.
  • a presently preferred form of sensor making use of Moiré patterns formed between the image of a projection grating reflected by the wafer surface and a fixed detection grating is described in European Patent Application EP-A-1 037 117 .
  • the level sensor should preferably measure the vertical position of a plurality of positions on the wafer surface simultaneously and for each position the sensor may measure the average height of a particular area, so averaging out unflatnesses of high spatial frequencies.
  • the vertical position of the substrate table is measured using the Z-interferometer, ZIF.
  • the Z-interferometer may, for example, be part of a three, five or six-axis interferometric metrology system such as that described in WO 99/28790 or WO 99/32940 , which documents are incorporated herein by reference.
  • the Z-interferometer system preferably measures the vertical position of the substrate table at a point having the same position in the XY plane as the calibrated measurement position of the level sensor LS.
  • this process is repeated with at least a second physical reference surface spaced apart, e.g. diagonally, from the first physical reference surface. Height measurements from two or more positions can then be used to define a reference plane.
  • a Z-interferometer of the type mentioned above is effectively a displacement sensor rather than an absolute sensor, and so requires zeroing, but provides a highly linear position measurement over a wide range.
  • suitable level sensors e.g. those mentioned above, may provide an absolute position measurement with respect to an externally defined reference plane (i.e. nominal zero) but over a smaller range.
  • the substrate table vertically under the level sensor until the physical reference surface(s) is (are) positioned at a nominal zero in the middle of the measurement range of the level sensor and to read out the current interferometer Z value.
  • One or more of these measurements on physical reference surfaces will establish the reference plane for the height mapping.
  • the Z-interferometer is then zeroed with reference to the reference plane.
  • the reference plane is related to the physical surface on the substrate table and the ZWafer height map is made independent of the initial zero position of the Z-interferometer at the measurement station and other local factors such as any unflatness in the base plate over which the substrate table is moved. Additionally, the height map is made independent of any drift in the zero position of the level sensor.
  • the substrate table is moved so that the wafer surface is scanned underneath the level sensor to make the height map.
  • the vertical position of the wafer surface and the vertical position of the substrate table are measured at a plurality of points of known XY position and subtracted from each other to give the wafer height at the known XY positions.
  • These wafer height values form the wafer height map which can be recorded in any suitable form.
  • the wafer height values and XY coordinates may be stored together in so-called indivisible pairs.
  • the points at which wafer height values are taken may be predetermined, e.g.
  • the motion of the substrate table during the height mapping scan is largely only in the XY plane.
  • the level sensor LS is of a type which only gives a reliable zero reading
  • the substrate table is also moved vertically to keep the wafer surface at the zero position of the level sensor.
  • the wafer height is then essentially derived from the Z movements of the substrate table, as measured by the Z-interferometer, necessary to maintain a zero readout from the level sensor.
  • a sensor with an appreciable linear range can allow the heights at a plurality of positions (e.g. an array of spots) to be measured simultaneously.
  • the wafer table is moved to the exposure station and, as shown in Figure 5 , the (physical) reference surface is positioned under the projection lens so as to allow a measurement of its vertical position relative to a reference point in the focal plane of the projection lens.
  • this is achieved using one or more transmission image sensors (described below) whose detector is physically connected to the reference surface used in the earlier measurements.
  • the transmission image sensor(s) can determine the vertical focus position of the projected image from the mask under the projection lens.
  • the reference plane can be related to the focal plane of the projection lens and an exposure scheme which keeps the wafer surface in optimum focus can be determined. In the prior art this is done by calculating a path for the substrate table in three-dimensions, e.g.
  • the shape of the focal plane is also adjusted to improve the focus using available manipulators in the projection lens. This is shown in Figure 8 .
  • the wafer surface WS includes significant unflatness, it is impossible to bring it into correct focus in a flat focal plane 11 across the entire area of the exposure slit of the projection beam PB. Instead, it is necessary to position the wafer at a position that minimizes the total or average defocus between the wafer surface WS and the flat focal plane 11.
  • the residual defocus can be minimized or eliminated by distorting the focal plane using available manipulators 22, 24, 26 in the projection system PL.
  • manipulators 22, 24, 26 may adjust the vertical, horizontal and/or rotational positions of elements 21, 23, 25 in the projection systems.
  • the manipulators used in the present invention may be provided for on-site adjustment of the projection lens, for compensating for transient effects, e.g.
  • lens heating caused by the projection beam or specifically for the present invention.
  • Lens elements used to correct field curvature caused by adjustments in the magnification of the system are particularly useful in the present invention.
  • the field curvature corrections can be changed, or field curvature deliberately introduced to improve focus on a non-flat substrate.
  • any other available manipulators which change the (relative) position and/or orientation of one or more lens elements may be used.
  • the invention may also make use of manipulators which change the shape and/or optical properties of elements in the projection system.
  • the degree of improvement afforded by the present invention will depend on the wafer surface and the number and effect of the available manipulators. As can be seen in Figure 8 , introducing a second order correction results in a focal plane 12 which is closer to the illustrated wafer surface and hence has a reduced defocus. Introducing a fourth order correction results in a focal plane 13 even closer to the wafer surface WS and hence further reduced defocus. If the projection system includes asymmetric elements and suitable manipulators, higher odd order corrections can also be made.
  • setpoints for p1, p2, etc. are determined in addition to setpoints for Z, Rx and Ry.
  • the setpoints can be determined using a least squares method so as to minimize the difference between the wafer map data and the focus plane of the exposure slit image, during the scanning motion.
  • the relative motion of the exposure slit image and wafer can be expressed as the slit moving relative to a static wafer.
  • the least squares criterion can then be expressed as, for each time t, finding the values Z(t), Rx(t), Ry(t), p1(t), p2(t), ... etc.
  • LSQ t 1 s . W ⁇ - / 2 s + / 2 s ⁇ - / 2 W - / 2 W w x , y , Z t , x . Ry t , y . Rx t - FP p ⁇ 1 t , p ⁇ 2 t , etc . d x d y where w(x , y , etc.
  • FP(p1(t), p2(t), etc.) defines the vertical position of the focal plane as a function of p1(t), p2(t), etc
  • s is the width of the exposure slit in the scanning direction and W its length perpendicular to the scanning direction.
  • the physical reference surface(s) is (are) preferably a surface in which a transmission image sensor (TIS) is inset.
  • TIS transmission image sensor
  • two sensors TIS1 and TIS2 are mounted on a fiducial plate mounted to the top surface of the substrate table (WT, WTa or WTb), at diagonally opposite positions outside the area covered by the wafer W.
  • the fiducial plate is made of a highly stable material with a very low coefficient of thermal expansion, e.g. Invar, and has a flat reflective upper surface which may carry markers used in alignment processes.
  • TIS1 and TIS2 are sensors used to determine directly the vertical (and horizontal) position of the aerial image of the projection lens.
  • the projection lens projects into space an image of a TIS pattern TIS-M provided on the mask MA and having contrasting light and dark regions.
  • the substrate table is then scanned horizontally (in one or preferably two directions) and vertically so that the aperture of the TIS passes through the space where the aerial image is expected to be.
  • the output of the photodetector will fluctuate. This procedure is repeated at different vertical levels.
  • the position at which the rate of change of amplitude of the photodetector output is highest indicates the position at which the image of TIS pattern has the greatest contrast and hence indicates the position of optimum focus. Thereby, a three-dimensional map of the focal plane can be derived.
  • An example of a TIS of this type is described in greater detail in US 4,540,277 , incorporated herein by reference.
  • a Reflection Image Sensor such as that described in US 5,144,363 , incorporated herein by reference, may also be used.
  • the surface of the TIS as the physical reference surface has the advantage that the TIS measurement directly relates the reference plane used for the height map to the focal plane of the projection lens, and so the height map can be employed directly to give height corrections for the substrate table during the exposure process.
  • Figure 6 shows the substrate table WT as positioned under the control of the Z-interferometer at a height determined by the height map so that the wafer surface is at the correct position under the projection lens PL.
  • the TIS surface may additionally carry reference markers whose position is detected using a through-the-lens (TTL) alignment system to align the substrate table to the mask.
  • TTL through-the-lens
  • An alignment system is described in EP-0 467 445 A , incorporated herein by reference, for example.
  • Alignment of individual exposure areas can also be carried out, or may be obviated by an alignment procedure carried out at the measurement stage to align the exposure areas to the reference markers on the substrate table.
  • an alignment procedure is described in EP-0 906 590 A , incorporated herein by reference, for example.
  • the height map generated by the present invention can be used to calculate in advance optimum Z, Rx, Ry, p1, p2, etc. position setpoints for the substrate table or projection system for each exposure. This avoids the time required for leveling in known apparatus that only measure wafer height when the wafer is positioned under the projection lens, and hence increases throughput.
  • the optimum Z, Rx, Ry, p1, p2, etc. setpoints may be calculated by various known mathematical techniques, for example using an iterative process to minimize defocus (defined as the distance between the wafer surface and the ideal focal plane), LSQ(t), integrated over the exposure area.
  • a further advantage is possible in the step-and-scan mode.
  • the projection lens projects an image of only part of the mask pattern onto a corresponding part of the exposure area.
  • the mask and substrate are then scanned in synchronism through the object and image focal planes of the projection system PL so that the entire mask pattern is imaged onto the whole exposure area.
  • the projection lens is held stationary and the mask and substrate are moved, it is often convenient to consider this process in terms of an image slit moving over the wafer surface.
  • the height map determined in advance by the present invention it is possible to calculate a sequence of Z, Rx, Ry, p1, p2, etc. setpoints matched to the XY scan path (usually, scanning takes place in only one direction, e.g. Y).
  • the sequence of setpoints can be optimized according to additional criteria, e.g. to minimize vertical accelerations or tilt motions that might reduce throughput or induce undesirable vibrations.
  • a scanning trajectory for the exposure can be calculated using a polynomial or spline fitting procedure.
  • the present invention aims to position the wafer at the optimum position in Z, Rx and Ry and adjust the shape of the focal plane for a given exposure
  • the variations in wafer surface height over the exposure area may be such that the wafer cannot be positioned and the focal plane shaped to give adequate focus over the entire area.
  • focus spots can result in an exposure failure.
  • failures can be predicted in advance and remedial action can be taken.
  • the wafer may be stripped and recoated without the detrimental effect of further processing a badly exposed wafer.
  • throughput may be enhanced by skipping exposures that can be predicted in advance to result in defective devices.
  • a control system 30 used in implementing the present invention is shown in Figure 9 .
  • data describing the wafer surface is supplied by wafer height map 31, which may comprise a memory in which a previously derived wafer height map has been stored, or a level sensor directly measuring the wafer surface, in real time, and data describing the focal plane from focal plane map 32.
  • the focal plane map 32 is generally a memory storing the results of periodic measurements of the focal plane shape, supplemented as necessary by a model of how the focal plane changes with varying imaging parameters. Where continuous or quasi-continuous measurement of the focal plane is possible, that may also be used.
  • the data describing the wafer surface and the focal plane shape is used by controller 33 to calculate setpoints for the substrate table position (Z, Rx and Ry) and projection lens parameters (p1, p2, etc.) which are supplied to servo controller 34 for table positioning and servo controller 35 for control of the manipulators 22, 24, 26 of the projection system PL.
  • the table positioning servo controller 34 may employ a feedback control using the table position as measured by the interferometric displacement measuring system IF.
  • the table position can also be used to control read-out from a memory 33a of setpoints calculated in advance.
  • the adjustments to projection system parameters p1, p2, etc. can be fed back from the servo controller 35 to the focal plane map 32.
  • the projection system may, as mentioned above, also be subject to adjustment to compensate for other, particularly transient, effects such as lens heating. Corrections to the projection system to effect the necessary compensations for such effects can be supplied by relevant control systems 36 and combined with adjustments for leveling and focusing according to the invention.
  • the control system 30 also includes a feedback from wafer height map 31 to servo controller 34 to allow control of the substrate table position in real time (on-the-fly). This feedback can be omitted if only off-axis leveling - in which the substrate table positions during the scan are stored in advance in memory - is to be performed.
  • the range of adjustment of the substrate table and its speed of response will be greater than those of the adjustable elements in the projection system.
  • the 0 th and 1 st order corrections are effectively height and tilt corrections whereas the higher order corrections represent variations in the wafer surface within the exposure slit which cannot therefore be compensated for by changing the height or tilt of the wafer surface.
  • the substrate table may be used to perform the 0 th or 1 st order correction, it is also contemplated that these corrections are performed by adjusting adjustable elements in the projection system. Where separation of 0 th and 1 st order from higher order correction is utilized, the separation may be done in the input data. For example, it would be possible to subtract the wafer surface and focal plane to derive a correction surface and for each exposure or point in the exposure path, then fit a flat, but inclined plane to the correction surface. The height of that flat plane at the center of the exposure slit determines the. necessary height correction (0 th order) and its inclination gives the necessary tilt corrections (1 st order). The flat inclined plane is then subtracted from the correction surface leaving the higher orders for correction by adjustment of the projection lens parameters.
  • adjustment of the projection lens parameters to achieve desired higher order corrections may cause unavoidable changes in the vertical position and inclination (0 th and 1 st order) of the focal plane.
  • an integrated control algorithm rather than separation of the higher and lower orders, may be preferable.
  • higher order corrections may be calculated first and any consequential effects in the lower order fed across into calculation of the necessary lower order corrections.
  • the higher order corrections in particular may be performed mainly to compensate for the wafer surface shape in the transverse direction.
  • This is because, with symmetric elements in the projection system, separate changes to the shape of the focal plane in the scanning and transverse directions are impossible.
  • a change in the curvature of the focal plane in the transverse direction would result in a change in the scanning direction but because of the greater dimension of the exposure slit in the transverse direction, the curvatures that are necessary to compensate for deviations in the transverse direction would only result in small vertical deviations at the extremes in the scanning direction. Further, focus deviations in the scanning direction are averaged out by the scanning motion, and in many cases can therefore be disregarded.
  • the wafer shape is primarily determined by previous process layers and a number of similar or identical dies are to be printed on one or more wafers, it may be possible to predict or calculate corrections only once for each die type in a wafer or batch of wafers.
  • the higher order wafer shape may be determined by previous process layers but superimposed on height and tilt variations across and between wafers and/or exposure areas. In such a case, the higher order corrections for each die type may be calculated in advance and combined with lower order corrections calculated for each exposure area.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Claims (16)

  1. Appareil de projection lithographique comprenant :
    un système de rayonnement (EX, IN, CO) pour fournir un faisceau de projection de rayonnement ;
    une structure de support (MT) pour supporter des moyens de mise en forme servant à mettre en forme le faisceau de projection conformément à un motif voulu ;
    une table de substrat (WT) pour supporter un substrat (W) ;
    un système de projection (PL) pour projeter le faisceau mis en forme sur une zone d'exposition du substrat, ledit système de projection ayant un plan focal et comprenant au moins un élément ajustable (21, 23, 25) capable de changer la forme du plan focal ; et
    des moyens de commande (30) agencés pour fonctionner pendant l'exposition d'une zone d'exposition par projection dudit faisceau mis en forme sur celle-ci pour commander ledit élément ajustable pour changer la forme dudit plan focal de manière à ce qu' il soit moins plat et qu'il se conforme plus étroitement au contour de surface de ladite zone d'exposition ; caractérisé en ce que
    ledit élément ajustable est un élément de lentille réfringent (21, 23, 25).
  2. Appareil selon la revendication 1 dans lequel lesdits moyens de commande comprennent une mémoire pour stocker des données (31) représentatives dudit contour de surface.
  3. Appareil selon la revendication 2 dans lequel ledit appareil comprend en outre une station de mesure (MS) ayant des moyens de mappage de hauteur de substrat agencés pour fonctionner avant une exposition pour mesurer le contour de surface de substrat d'au moins une zone d'exposition, pour stockage dans ladite mémoire.
  4. Appareil selon la revendication 2 dans lequel lesdits moyens de commande (30) comprennent également une interface pour recevoir des données représentatives dudit contour de surface en provenance d'un dispositif externe.
  5. Appareil selon la revendication 2, 3 ou 4 dans lequel lesdits moyens de commande (30) sont agencés pour calculer des ajustements voulus dudit élément ajustable pour une exposition donnée avant cette exposition.
  6. Appareil selon la revendication 1 dans lequel ledit appareil comprend en outre un capteur pour mesurer la position de la surface de substrat en une pluralité de points dans ladite zone d'exposition pendant une exposition.
  7. Appareil selon l'une quelconque des revendications précédentes comprenant également des moyens de positionnement pour déplacer ladite table de substrat (WT) pour positionner le substrat à une position et/ou orientation voulue et dans lequel lesdits moyens de commande (30) sont également opérationnels pour commander lesdits moyens de positionnement pour positionner le substrat.
  8. Appareil selon la revendication 7 dans lequel lesdits moyens de commande (30) sont adaptés pour commander lesdits moyens de positionnement pour effectuer des corrections d'ordre faible pour amener la surface dudit substrat (W) sur ladite zone d'exposition en conformité plus étroite avec ledit plan focal et pour commander ledit élément ajustable pour effectuer des corrections d'ordre élevé.
  9. Appareil selon la revendication 8 dans lequel lesdites corrections d'ordre faible comprennent des corrections de position et d'orientation.
  10. Appareil selon la revendication 8 ou 9 dans lequel lesdits moyens de commande (30) sont adaptés pour commander ledit système de positionnement pour effectuer des corrections d'ordre faible pour compenser des effets d'ordre faible dus à des ajustements dudit élément ajustable.
  11. Appareil selon l'une quelconque des revendications précédentes dans lequel ledit élément ajustable (21, 23, 25) est une lentille de correction de courbure de champ.
  12. Procédé de fabrication d'un dispositif comprenant les étapes de :
    fournir un substrat (W) qui est au moins partiellement recouvert d'une couche de matériau sensible au rayonnement ;
    fournir un faisceau de projection de rayonnement utilisant un système de rayonnement (EX, IN, CO) ;
    utiliser des moyens de mise en forme (MA) pour doter le faisceau de projection d'un motif dans sa section transversale ;
    projeter le faisceau de rayonnement mis en forme sur une zone d'exposition de la couche de matériau sensible au rayonnement en utilisant un système de projection (PL), ledit système de projection ayant un plan focal et comprenant au moins un élément ajustable (21, 23, 25) capable de changer la forme du plan focal ; et
    commander ledit élément ajustable (21, 23, 25), pendant l'étape de projection du faisceau mis en forme sur une zone d'exposition, pour changer la forme dudit plan focal de manière à ce qu'il soit moins plat et qu'il se conforme plus étroitement au contour de surface de ladite zone d'exposition ; caractérisé en ce que :
    ledit élément ajustable est un élément de lentille réfringent (21, 23, 25).
  13. Procédé selon la revendication 12 comprenant en outre l'étape de mesurer le contour de surface de ladite zone de l'exposition avant l'étape de reproduction.
  14. Procédé selon la revendication 13 dans lequel l'étape de mesure est réalisée en utilisant une station de mesure (MS) dans l'appareil lithographique ou un outil de qualification séparé.
  15. Procédé selon la revendication 13 ou 14 comprenant en outre l'étape de calculer des ajustements de l'élément ajustable (21, 23, 25) pour l'imagerie d'une zone d'exposition donnée avant l'étape d'imagerie de cette zone d'exposition.
  16. Procédé selon la revendication 15 dans lequel une pluralité de zones d'exposition similaires est imagée et des ajustements calculés pendant ladite étape de calcul d'ajustements sont utilisés lors de l'imagerie d'une pluralité de zones d'exposition.
EP02250785A 2001-02-08 2002-02-06 Appareil lithographique et méthode de fabrication d'un dispositif Expired - Lifetime EP1231515B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02250785A EP1231515B1 (fr) 2001-02-08 2002-02-06 Appareil lithographique et méthode de fabrication d'un dispositif

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP01301116A EP1231513A1 (fr) 2001-02-08 2001-02-08 Appareil de projection lithographique avec surface réglable de focalisation
EP01301116 2001-02-08
EP02250785A EP1231515B1 (fr) 2001-02-08 2002-02-06 Appareil lithographique et méthode de fabrication d'un dispositif

Publications (2)

Publication Number Publication Date
EP1231515A1 EP1231515A1 (fr) 2002-08-14
EP1231515B1 true EP1231515B1 (fr) 2008-11-05

Family

ID=26077086

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02250785A Expired - Lifetime EP1231515B1 (fr) 2001-02-08 2002-02-06 Appareil lithographique et méthode de fabrication d'un dispositif

Country Status (1)

Country Link
EP (1) EP1231515B1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006053751A2 (fr) * 2004-11-18 2006-05-26 Carl Zeiss Smt Ag Objectif de projection d'une installation d'eclairage de projection microlithographique
US7525638B2 (en) 2005-03-23 2009-04-28 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
JP5069232B2 (ja) 2005-07-25 2012-11-07 カール・ツァイス・エスエムティー・ゲーエムベーハー マイクロリソグラフィ投影露光装置の投影対物レンズ
US20110261344A1 (en) * 2009-12-31 2011-10-27 Mapper Lithography Ip B.V. Exposure method
JP5890139B2 (ja) * 2011-09-30 2016-03-22 株式会社Ｓｃｒｅｅｎホールディングス 描画装置およびその焦点調整方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5142132A (en) * 1990-11-05 1992-08-25 Litel Instruments Adaptive optic wafer stepper illumination system

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61196532A (ja) * 1985-02-26 1986-08-30 Canon Inc 露光装置
EP0480616B1 (fr) * 1990-10-08 1997-08-20 Canon Kabushiki Kaisha Appareil d'exposition par projection avec un dispositif pour compenser l'aberration d'une lentille de projection
US5202748A (en) * 1991-06-07 1993-04-13 Litel Instruments In situ process control system for steppers

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5142132A (en) * 1990-11-05 1992-08-25 Litel Instruments Adaptive optic wafer stepper illumination system

Also Published As

Publication number Publication date
EP1231515A1 (fr) 2002-08-14

Similar Documents

Publication Publication Date Title
US6741331B2 (en) Lithographic apparatus with improved exposure area focus, device manufacturing method, and device manufactured thereby
CN100555086C (zh) 用于光刻装置的水平传感器
US6646729B2 (en) Method of measuring aberration in an optical imaging system
KR100554258B1 (ko) 리소그래피 투영장치 교정방법 및 상기 방법을 적용할 수있는 장치
JP4352042B2 (ja) オーバレイを減少させるための基板テーブルまたはマスクテーブルの表面平坦度情報の使用
US7116401B2 (en) Lithographic projection apparatus using catoptrics in an optical sensor system, optical arrangement, method of measuring, and device manufacturing method
JP4563923B2 (ja) 位置合わせ方式最適化方法
EP1975723A1 (fr) Appareil de projection lithographique et procédé de fabrication de dispositif utilisant un appareil de projection lithographique
US20130162964A1 (en) Lithographic Apparatus and Device Manufacturing Method
US7298455B2 (en) Lithographic apparatus and device manufacturing method
US20050210438A1 (en) Modification of an image of a pattern during an imaging process
US7583359B2 (en) Reduction of fit error due to non-uniform sample distribution
US20090042139A1 (en) Exposure method and electronic device manufacturing method
KR20100016315A (ko) 노광 장치, 노광 방법 및 전자 디바이스 제조 방법
KR100602917B1 (ko) 리소그래피장치, 디바이스 제조방법 및 이에 따라 제조된디바이스
EP1128217B1 (fr) Méthode de mesure des aberrations dans un système optique de formation d'image
US7453063B2 (en) Calibration substrate and method for calibrating a lithographic apparatus
EP1231515B1 (fr) Appareil lithographique et méthode de fabrication d'un dispositif
US6987555B2 (en) Lithographic apparatus, device manufacturing method, and device manufactured thereby
US6897947B1 (en) Method of measuring aberration in an optical imaging system
US7379156B2 (en) Lithographic apparatus and device manufacturing method
EP1357435A1 (fr) Appareil lithographique et méthode de fabrication d'un dispositif

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 20030120

17Q First examination report despatched

Effective date: 20030321

AKX Designation fees paid

Designated state(s): DE FR GB IT NL

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: ASML NETHERLANDS B.V.

APBN Date of receipt of notice of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA2E

APBR Date of receipt of statement of grounds of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA3E

APAF Appeal reference modified

Free format text: ORIGINAL CODE: EPIDOSCREFNE

APAF Appeal reference modified

Free format text: ORIGINAL CODE: EPIDOSCREFNE

APBT Appeal procedure closed

Free format text: ORIGINAL CODE: EPIDOSNNOA9E

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT NL

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REF Corresponds to:

Ref document number: 60229680

Country of ref document: DE

Date of ref document: 20081218

Kind code of ref document: P

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081105

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20090219

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20090219

Year of fee payment: 8

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20090806

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20090213

Year of fee payment: 8

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20100206

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20101029

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100301

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100901

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100206

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081105